Studies on the use of thermotherapy against ‘Candidatus Liberibacter asiaticus’
Research studies have been conducted in the USA on the use of thermotherapy to eliminate ‘Candidatus Liberibacter asiaticus’ (EPPO A1 List) from infected citrus trees. Results have shown that continuous thermal exposure to 40 to 42°C for a minimum period of 48 h was sufficient to significantly reduce the bacterial titre or eliminate ‘Ca. Liberibacter asiaticus’ from diseased citrus trees (young potted-plants). During these experiments, all surviving plants showed healthy vigorous growth and remained disease free for more than 2 years following the treatment (when not exposed to re-infection). It is concluded that thermotherapy could be used as a sanitation method during breeding programmes or the production of healthy planting material. Further studies are needed to evaluate whether thermotherapy could also be used, possibly in combination with chemical treatments, for trees grown in commercial groves and private gardens.
Sources
Hoffman MT, Doud MS, Williams L, Zhang MQ, Ding F, Stover E, Hall D, Zhang S, Jones L, Gooch M, Fleites L, Dixon W, Gabriel D, Duan YP (2013) Heat treatment eliminates ‘Candidatus Liberibacter asiaticus’ from infected citrus trees under controlled conditions. Phytopathology 103(1), 15-22.